An EMG/NCV test involves two individual tests that, when performed together, gives the doctor information they need to determine how the nerves and muscles are responding to specific types of stimuli. An EMG, or electromyography, is a specific test that is used to determine how well muscles respond to the signals that are sent to them by the brain and along the nerve pathways. An NCV test, or nerve conduction velocity test, determines how fast signals travel along the nerves to the rest of the body. When both tests are performed together, the doctor is able to determine how quickly the muscles receive the signals and again, how fast they respond to those signals.
During an EMG/NCV test, the doctor will begin by having the patient remove any metal objects from their body (ex. earrings). Electrodes will then be placed at the starting point of where the nerve impulses will be sent from. After this, another set of electrodes will be placed near the destination point. An example of this would be near the spine and the fingertips. An electrical impulse will be sent from the first set of electrodes to the second while the doctor monitors the transmission. The machine will record the amount of time the impulse takes to get from the origin to the destination. The impulse that is sent through the body is very weak and may produce an uncomfortable sensation, but it is not painful.
Both the EMG and the NCV tests are performed together because one test produces the results needed to assess the second test. The speed at which the nerves travel will give an indication as to how quickly the muscles respond. While the tests can be performed separately and produce similar results, it is much easier to perform the together so the patient only has to go through the testing one time. While pain and discomfort are minimal, performing the test more than two or three times may begin to cause pain. Because the results of the test are presented together, it seems natural to perform both tests at the same time.